The primary goal of this project is to determine how acoustic information is represented in the auditory cortex. Though there have been numerous electrophysiological studies that characterize the responses of cortical neurons to sound, the underlying cellular and network mechanisms are still unclear. Here, we will use a combination of experiments and computer simulations to elucidate how neural networks in cortex process and transmit information. In the experiments of Aim 1, simultaneous whole-cell recordings will be performed from excitatory and inhibitory cells in cortical layers 2/3, 4, and 5 to determine the network architecture and characterize the synaptic connections between the neurons. In the experiments of Aim 2, the patterns of connections between neurons between neurons in layer 4 & layer 2/3 and between layer 2/3 & layer L5 will be characterized. This will provide information as to how signals are transformed from network to network. Finally, in Aim 3, the data obtained from the experiments will be used to construct a realistic model of auditory cortex. These experiments and simulations will provide basic information about cortical circuitry as well as provide insights as to how auditory signals are processed in cortex. The data and simulations will shed light on how hearing disorders are manifested at the cellular and network levels and conversely, how dysfunction at the cellular and network levels translate to hearing deficits.